Battery pack

ABSTRACT

In accordance with the present invention, an improved battery pack is employed. The battery pack includes a housing with opposing walls, a plurality of cells disposed within the housing, at least two terminals electrically connected to the cells, a latching mechanism disposed on each opposing wall for latching the battery pack to a cordless device, each latching mechanism including a latch and a button disposed on the wall for moving the latch between unlatching and latching positions, the latching buttons being disposed along a first plane, the first plane being substantially vertical, wherein the number of cells disposed along the first plane is smaller than the number of cells disposed along a second plane substantially parallel to the first plane. The battery pack may also include a stacked cell disposed on the plurality of cells. The stacked cell may be disposed along the first plane. However, the stacked cell is not included in the number of cells disposed along the first plane.

This application is a continuation of Ser. No. 09/354,405, filed Jul.15, 1999, now U.S. Pat. No. 6,326,101.

FIELD OF THE INVENTION

This invention relates generally to battery packs and, moreparticularly, to battery packs for cordless power tools.

BACKGROUND OF THE INVENTION

Cordless products which use rechargeable batteries are prevalentthroughout the workplace as well as in the home. From housewares topower tools, rechargeable batteries are used in numerous devices.Ordinarily, nickel-cadmium or nickel-metal hydride battery cells areused in these devices. Since the devices use a plurality of batterycells, the battery cells are ordinarily packaged as battery packs. Thesebattery packs couple with the cordless devices and secure to the device.The battery pack may be removed from the cordless device and charged ina battery charger or charged in the cordless device itself.

FIGS. 1-3 illustrate a typical battery pack 10, which includes a bottomhousing 11, a plurality of cells 12 disposed within the housing, a cell13 disposed on the plurality of cells 12, and a terminal block 14disposed on cell 13. Persons skilled in the art will recognize that theterminal block 14 and cells 12, 13 are electrically connected in amanner well known in the art, and that such electrical connections arenot shown for the sake of clarity. Also, persons skilled in the art arereferred to U.S. Pat. No. 5,144,217 for further information on a typicalprior art terminal block 14.

A pack cover 15 carrying a tower 16 is disposed on housing 11 so as tocontain cells 12, 13 therein. Tower 16 has an aperture 17 exposingterminal block 14 for electrical connection to the power tool (notshown). The pack cover 15 may be held in place via screws 19, or othermeans, so as adhesives, molten plastic, etc.

Typical battery packs include at least one latch mechanism 18 forlatching the battery pack 10 to the power tool, or cordless device.Latch mechanism 18 typically includes a button 18B disposed on housing11, a latch hook 18L movably connected to button 18B and movable betweena latching position and an unlatched position, and a spring 18S forbiasing latch hook 18L towards the latching position. Accordingly, inorder to unlatch a battery pack from the power tool, the user needs topress button(s) 18B with one hand, moving latch hook 18L towards theunlatched position, and pull out the battery pack 10, while holding thepower tool with the other hand.

Typically battery packs 10 have two buttons 18B on opposing walls ofhousing 11. Accordingly, the operator needs to bridge the compositedistance of A, B and C, i.e., the lengths along the housing 11, in orderto press both buttons 18B and unlatch battery pack 10. However, as thenumber of cells 12 is increased to obtain higher voltages, the compositedistance (A+B+C) is also increased, until the operator cannot easilyreach both buttons 18B.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved battery pack isemployed. The battery pack includes a housing with opposing walls, aplurality of cells disposed within the housing, at least two terminalselectrically connected to the cells, a latching mechanism disposed oneach opposing wall for latching the battery pack to a cordless device,each latching mechanism including a latch and a button disposed on thewall for moving the latch between unlatching and latching positions, thelatching buttons being disposed along a first plane, the first planebeing substantially vertical, wherein the number of cells disposed alongthe first plane is smaller than the number of cells disposed along asecond plane substantially parallel to the first plane. The battery packmay also include a stacked cell disposed on the plurality of cells. Thestacked cell may be disposed along the first plane. However, the stackedcell is not included in the number of cells disposed along the firstplane.

Additional features and benefits of the present invention are described,and will be apparent from, the accompanying drawings and the detaileddescription below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of theinvention according to the practical application of the principlesthereof, and in which:

FIG. 1 is an exploded perspective view of a prior art battery pack;

FIG. 2 is a rear view of the lower portion of the battery pack of FIG.1;

FIG. 3 is a top plan view of the lower portion of FIG. 2 along lineIII—III;

FIG. 4 is a side view of a lower portion of the improved battery packaccording to a first embodiment of the present invention;

FIG. 5 is a bottom plan view of the lower portion of FIG. 4 along lineV—V;

FIG. 6 is a top plan view of the lower portion of FIG. 4 along lineVI—VI;

FIG. 7 is a rear elevational view of the lower portion of FIG. 4 alongline VII—VII; and

FIG. 8 is a side view of a lower portion of the improved battery packaccording to a second embodiment of the present invention.

DETAILED DESCRIPTION

The invention is now described with reference to the accompanyingfigures, wherein like numerals designate like parts. Referring to FIGS.4-7, the battery pack 100 has a housing 11A, latch mechanisms 18thereon, and cells 12 within housing 11A. Battery pack 100 may also havea pack cover 15, tower 16, terminal block 14 and/or cell 13 as taught inthe prior art.

Preferably each of two opposing walls of housing 11A has a front portion11F, a rear portion 11R and a channel portion 11C disposed between frontand rear portions 11F, 11R. Preferably channel portion 11C is depressedrelative to front and rear portions 11F, 11R. In other words, whilefront and rear portions 11F, 11R may be substantially coplanar, channelportion 11C is not.

Channel portion 11C may include a surface 11S. Preferably the distancebetween surface 11S and center plane Z is smaller than the distancebetween center plane Z and front and/or rearportions 11F, 11R. Surface11S may be inclined or substantially parallel to front and/or rearportions 11F, 11R (though not coplanar).

Persons skilled in the art will recognize that button 18B may bedisposed on surface 11S or within channel portion 11C. However, personsskilled in the art should recognize that buttons 18B may be disposedoutside of channel portion 11C.

By providing such channel portions 11C, the effective distance betweenlatch buttons 18B, i.e, the composite distance, is about D+E+F, and thusis smaller than composite distance A+B+C, thus providing a moreergonomic access to the latching buttons 18B. Preferable, distance D+E+Fis about or less than 4 inches, whereas the distance A+B+C is about 4.5inches.

In order to obtain such arrangement, it is preferable to arrange cells12 so that the number of cells 12 disposed between the latching buttons18, or along plane X, is smaller than the number of cells 12 disposedelsewhere in housing Y, e.g., along plane Y. Such cell arrangementpermits the surface 11S to be closer to the center plane Z.

A second embodiment is shown in FIG. 8, where like numerals refer tolike parts. The teachings of the first embodiment are incorporatedherein. Housing 11B, as before, may carry latching buttons 18B, and mayhave front and rear portions 11F, 11R. Housing 11B may also have abottom surface 11BP, which is substantially planar along plane H. Achannel portion 11D is preferably disposed between front and rearportions 11F, 11R, and/or below latching buttons 18B. Preferably,channel portion 11D has a surface 11DP which is disposed between buttons18B and plane H. In other words, the distance between surface 11DP andbuttons 18B is smaller than the distance between buttons 18B and planeH. Similarly, the distance between surface 11DP and top housing plane Gis smaller than the distance between planes G and H, i.e., the height ofhousing 11.

In order to obtain such arrangement, it is preferable to arrange atleast one of the cells 12 (cell 12H) so that it lays horizontally, asopposed to the other cells 12 which stand vertically, in housing 11.Such cell arrangement permits the surface 11DP to be closer to thebuttons 18B, etc.

Housing 11 may also have vent holes 11H disposed thereon. In addition,housing 11 may have ribs 11R to help locate the cells 12 within housing11. Preferably holes 11H are disposed between ribs 11R and/or the wallsof housing 11.

Persons skilled in the art may recognize other alternatives to the meansdisclosed herein. However, all these additions and/or alterations areconsidered to be equivalents of the present invention.

What is claimed is:
 1. A battery pack comprising: a housing comprising afirst pair of opposing walls and a second pair of opposing walls, thesecond pair being transverse to the first pair; a plurality of cellsdisposed within the housing; at least two terminals electricallyconnected to the cells; a latching mechanism disposed on each wall ofthe first pair of opposing walls for latching the battery pack to acordless device, each latching mechanism comprising a latch, and abutton disposed on each wall of the first pair for moving the latchbetween unlatching and latching positions, the latching buttons beingdisposed along a first plane, the first plane being substantiallyvertical; wherein number of cells disposed along the first plane issmaller than number of cells disposed along a second plane substantiallyparallel to the first plane.
 2. The battery pack of claim 1, furthercomprising a stacked cell disposed on the plurality of cells.
 3. Thebattery pack of claim 2, wherein the stacked cell is disposed along thefirst plane.
 4. The battery pack of claim 3, wherein the stacked cell isnot included in the number of cells disposed along the first plane. 5.The battery pack of claim 1, wherein at least one wall has first andsecond portions.
 6. The battery pack of claim 5, wherein at least one ofthe buttons is disposed on the second portion of the at least one of thewalls.
 7. The battery pack of claim 5, wherein the first and secondportions comprise substantially non-coplanar surfaces.
 8. The batterypack of claim 7, wherein distance between the second portion surface anda center plane dissecting the housing is smaller than distance betweenthe first portion surface and the center plane.
 9. The battery pack ofclaim 8, wherein the first portion surface is substantially vertical.10. The battery pack of claim 8, wherein the second portion surface issubstantially vertical.
 11. The battery pack of claim 8, wherein thesecond portion surface is inclined.
 12. The battery pack of claim 8,wherein at least one of the buttons is disposed on the second portionsurface of the at least one of the walls.
 13. The battery pack of claim1, wherein the cells are vertical.
 14. The battery pack of claim 1,wherein at least one of the cells is vertical.
 15. The battery pack ofclaim 1, wherein the housing comprises a floor.
 16. The battery pack ofclaim 15, wherein the floor is substantially horizontal.
 17. The batterypack of claim 15, wherein the latching buttons are disposed along afirst line located at a first distance from the floor.
 18. The batterypack of claim 17, wherein distance between the latching buttons alongperiphery of the housing is smaller than distance between two pointsalong periphery of the housing, the two points being contained within asecond line parallel to the first line and located at the first distancefrom the floor.
 19. A battery pack comprising: a housing comprising afloor, a first pair of opposing walls connected to the floor, at leastone wall of said first pair having first and second portions, and asecond pair of opposing walls connected the floor, the second pair ofopposing walls being transverse to the first pair of opposing walls; aplurality of cells disposed within the housing; at least two terminalselectrically connected to the cells; a latching mechanism disposed oneach wall of said first pair for latching the battery pack to a cordlessdevice, each latching mechanism comprising a latch, and a buttondisposed on each wall of said pair for moving the latch betweenunlatching and latching positions, the latching buttons being disposedalong a first line located at a first distance from the floor; whereindistance between the latching buttons along periphery of the housing issmaller than distance between two points along periphery of the housing,the two points being contained within a second line parallel to thefirst line and located at the first distance from the floor and in thefirst portion.
 20. The battery pack of claim 19, wherein the first andsecond portions comprise substantially non-coplanar surfaces.
 21. Thebattery pack of claim 20, wherein distance between the second portionsurface and a center plane dissecting the housing is smaller thandistance between the first portion surface and the center plane.
 22. Thebattery pack of claim 20, wherein the first portion surface issubstantially vertical.
 23. The battery pack of claim 20, wherein thesecond portion surface is substantially vertical.
 24. The battery packof claim 20, wherein the second portion surface is inclined.
 25. Thebattery pack of claim 20, wherein at least one of the buttons isdisposed on the second portion surface of the at least one of the walls.26. The battery pack of claim 19, wherein the cells are vertical. 27.The battery pack of claim 19, wherein at least one of the cells isvertical.
 28. The battery pack of claim 19, wherein number of cellsdisposed along a first plane between the latching buttons is smallerthan number of cells disposed along a second plane substantiallyparallel to the first plane.
 29. The battery pack of claim 28, furthercomprising a stacked cell disposed on the plurality of cells.
 30. Thebattery pack of claim 29, wherein the stacked cell is disposed along thefirst plane.
 31. The battery pack of claim 30, wherein the stacked cellis not included in the number of cells disposed along the first plane.